Astragalus coccineus Brandegee

Authors

Rupert C. Barneby

Authority

Barneby, Rupert C. 1964. Atlas of North American Astragalus. Mem. New York Bot. Gard. 13(2): 597-1188.

Family

Fabaceae

Scientific Name

Astragalus coccineus (Parry) Brandegee

Synonyms

Xylophacos coccineus (Brand) A.Heller, , Astragalus purshii var. coccineus Parry

Description

Species Description - Low, tufted, obligately acaulescent, mature plants composed of 1—several crowns clustered on the head of a woody taproot and beset with a thatch of persistent stipules and stout (but not rigid) recurving petioles, densely villous-tomentose throughout with mixed shorter curly hairs and longer nearly straight, ascending or spreading ones up to 1.5—2.5 mm. long, the herbage at first white-silky, becoming tomentose late in the season; stipules papery-membranous beneath the vesture, lanceolate or deltoid-acumminate, 6—10 mm. long, ± semiamplexicaul; leaves radical, (3) 4—10 cm. long, with stout petiole and 7—15 obovate-cuneate to broadly oblanceolate and obtuse, or elliptic and subacute, thick-textured, flat or loosely folded leaflets (3) 5—14 mm. long; peduncles stout, (2) 4—10 cm. long, ascending at anthesis, procumbent in fruit; racemes shortly but loosely, sometimes subcapitately (3) 5—10-flowered, the flowers ascending at a narrow angle, the axis little elongating, 0.5—2.5 cm. long in fruit; bracts membranous, lance-acuminate, 5—7 mm. long; pedicels ascending, or a little arched outward in age, at anthesis 3-4 mm., in fruit thickened, 4—5 mm. long; bracteoles commonly 0, rarely a minute scale concealed by the vesture; calyx 18—24 mm. long, villous with white and often some black hairs, the subsymmetric disc 2-2.7 mm. deep, the membranous, reddish, cylindric tube (12) 13.5-16 mm. long, 4.6-6 mm. in diameter, the firm, subulate or lanceolate teeth 3.5-8 mm. long; petals scarlet, drying crimson, the fold of the banner whitish with red veins; banner recurved through 20-30°, broadly oblanceolate, either obtuse to very shallowly emarginate or broadly triangular-subulate at apex, 3.5-4.1 cm. long, 1.2-1.7 cm. wide; wings slightly shorter, 34.5-37.5 mm. long, the claws 1.7-2.1 cm., the linear-oblong or -lanceolate, obtuse or obliquely truncate, straight blades 1.8-2 cm. long, 2.8-3.8 mm. wide; keel ± equaling the banner and surpassing the wings, 3.5-4 cm. long, the claws 17.5-21 mm., the erect, subsymmetrically elliptic-oblanceolate, triangular-acute blades 1.9-2.1 cm. long, 5.2-6.6 mm. wide; anthers 1.2-1.5 mm. long; pod ascending (humistrate), obliquely lance-ovoid, narrowly ovoid-ellipsoid, or lunately ellipsoid, 2.5-4 cm. long, 9-12 mm. in diameter, rounded or broadly cuneate at base, obcompressed and either flattened or sulcate both ventrally and dorsally in the lower Vi, thence passing upward into an incurved, acuminate, laterally flattened beak, the moderately fleshy valves becoming leathery, faintly rugulose-reticulate, and ± 0.3 mm. thick when ripe, not inflexed, the surface of the valves concealed by the dense vesture of shorter curly together with longer, straighter, and spreading hairs up to 2-3 mm. long; dehiscence apical, through the gaping beak, after falling; seeds brown or dark purplish-brown, smooth or pitted, dull, 2.5-4.2 mm. long.

Distribution and Ecology - Open gravelly ridges and canyon benches of desert mountains, commonly on decomposed granite, with piñon, juniper, or sagebrush, 2100-7000 feet, sometimes carried down along washes into the Larrea belt as low as 150 feet, but hardly persistent there, widespread and locally plentiful in scattered stations around the north and west edges of the Mohave and Colorado Deserts, from Owens Valley and Death Valley south to the north slope of the San Gabriel, San Bernardino, and Little San Bernardino Mountains, and from the San Jacinto Mountains south into extreme northern Baja California; also disjunctly on the Kofa Mountains, Yuma County, Arizona. A report from the Charleston Mountains, southern Nevada, was based on a specimen of A. Newberryi (Purpus in 1898, UC).— Map No. 85. —March to early June.

Discussion

No astragalus can surpass the splendid effect of A. coccineus flowering after a rainy spring, and few come close to rivaling it. The fiery blood-red of the long, narrow flowers is accentuated by the tufts of white or ashen foliage, and in the clear desert air assumes a brilliant transparency. Only two other American astragali have red flowers, the Mexican A. Helleri and A. sanguineus, both strongly caulescent plants with fully bilocular pods. Fruiting specimens are sometimes difficult to distinguish from A. Newberryi, for the habit of growth and especially the hard, thickened crowns beset with stiff, recurved bases of the leaf-stalks are almost identical. The pod, however, is ordinarily longer and consequently of a more slender, fusiform outline, and vestiges of the characteristic petals can often be found clinging with the papery-marcescent calyx about the base of the fruit. The pod of A. coccineus most closely resembles that of A. funereus, a rare Death Valley endemic which Jones referred to subsect. Coccinei; but this is at least potentially caulescent, and the foliage has the soft cottony-pannose vesture of subsect. Eriocarpi.

Although the scarlet coloring of the flower is most immediately striking and memorable, its form is of equal interest. The petals are irregularly graduated, the wings being shorter than the banner and keel, and all stand almost vertically erect out of the calyx, the banner being much less strongly recurved than in related Argophylli. The prominent, subsymmetrically elliptic, subacute blades of the keel are peculiar to the scarlet milk-vetch. The papilionaceous corolla has been modified so as to appear (superficially) tubular or tubular-infundibuliform, a type attractive to hummingbirds, whose partiality to the red segment of the spectrum is well known. Whether this is a case of cause and effect or merely a random modification is hard to say. I can only marvel at the abrupt acquisition of a spectacularly altered flower by a plant which has retained all other features of its closer kindred.

Objects

Specimen - 01247678, V. Duran 545, Astragalus coccineus (Parry) Brandegee, Fabaceae (152.0), Magnoliophyta; North America, United States of America, California

Specimen - 01247677, A. A. Heller 8190, Astragalus coccineus (Parry) Brandegee, Fabaceae (152.0), Magnoliophyta; North America, United States of America, California, Inyo Co.

Distribution

California United States of America North America| Arizona United States of America North America| Baja California Mexico North America|